It is unfortunate that AIR doesn't get more press action than it already does. If you need to develop client-side apps and are already familiar with web technologies (HTML/JS), you can jump in swimming. You get a brain-dead simple API that adds common OS-related tasks like loading and saving files. And it's completely cross-platform!
My small company builds custom AIR apps for clients in real-time. Take the command-line compiler, a dash of AWS's services and database-driven configuration files and the system builds one-of-a-kind cross-platform apps in seconds. It's the closest thing to fill-in-the-blank software that I've found.